1. Cheap things are not good. Although it sounds cruel, it is true most of the time. Don't trust the "king of cost performance" with hundreds of dollars.
2. The purification process of collagen is extremely difficult, and nano-scale purification process is enough. Therefore, nano-collagen is better than small-molecular collagen, and small-molecular collagen is better than large-molecular collagen. Most of the market prices below 1000 yuan are small molecular collagen, and those below 300 yuan claim to be small molecular collagen, which can basically be blacklisted.
3. Collagen is nourished from the inside out. According to the law of human metabolism, a cycle is 93 days, so those who promise to get immediate results in 30 days or even less are basically unreliable.